Rio+20 Summit opens with promises, criticisms

Story highlights

More than 50,000 delegates are expected in Rio de Janeiro for the Rio+20 Summit

The conference is aimed at promoting economic growth and poverty reduction

Preserving the planet's resources also a main topic of discussion

The U.S. delegation is headed by Secretary of State Hillary Clinton

World leaders poured into Rio de Janeiro on Wednesday, 20 years after the landmark Earth Summit, to commit themselves to a new roadmap for sustainable development -- with that roadmap already under fire for failing to set firm goals.

The three-day Rio+20 Summit opened with words of warning from the United Nations Secretary-General Ban Ki-moon.

"Let us match words with actions," he told reporters. "Our scarcest resource is time, and it is running out."

More than 50,000 delegates are expected to participate in the conference, which is aimed at promoting economic growth and poverty reduction while simultaneously preserving the planet's resources.

Many member states nonetheless praised the host government for getting all countries to finally agree on a document.

The U.S. delegation, represented by Secretary of State Hillary Clinton, called the summit a "historic opportunity to communicate the value of sustainable development and help galvanize real-world, collaborative action to stimulate growth, protect the environment and provide a healthy future for our citizens."

Businesses played a much bigger role at this summit than they did 20 years ago, with many observers saying they have actually taken the lead by providing real examples of sustainable development.

Georg Kell, head of the U.N. Global Compact, said his group hopes to increase the number of companies agreeing to concrete sustainable development goals to 20,000, from 7,000.

"I hope also we will be able to inspire governments to have the courage to set the right incentives," he told CNN.

On Wednesday, the first session of the high-level summit was addressed by 17-year-old activist Brittany Trilford of New Zealand, who challenged leaders: "Are you here to save face or are you here to save us?"

Ban suggested that the highly criticized final document could still be revised by world leaders before the summit ends on Friday.

When asked by reporters about that possibility, he responded: "Why do we have a summit meeting? Why have I been inviting and urging leaders, heads of state and government? They are the ones who can make political decisions, who can make a choice."